1. Field of the Invention
The present invention relates to a fuel filler port closing apparatus provided with a flapper for opening and closing an opening of a nozzle guide for guiding an fuel filling nozzle inserted from an opening of a filler neck (a fuel filler port), the flapper being pushed and biased upwardly by a torsion coil spring and being rotatable towards the lower side.
2. Description of the Related Art
A filler neck cap screwed into a filler neck has an advantage of being easy to ensure sealability of the filler neck. However, it has a disadvantage in that the attachment/detachment task of the filler neck cap is cumbersome. There is also a possibility that sealing may be insufficient if a screw-in operation of the cap is inappropriate or that the detached filler neck cap may get lost. Considering these problems, a fuel filler port closing apparatus provided with a flapper is proposed. Such a fuel filler port closing apparatus has the flapper which opens by rotating downwardly (towards the lower side) when pushed by the fuel filling nozzle inserted from the outside and closes by rotating upwardly (towards the upper side) when the fuel filling nozzle is removed. According to the fuel filler port closing apparatus, forgetting to tighten the filler neck cap can not occur. Further, since the filler neck cap is closed immediately before the fuel filling nozzle is inserted and is opened only when the fuel filling nozzle is inserted (i.e., during actual fuel feeding task), discharge of fuel vapor can be suppressed at minimum.
The conventional fuel filler port closing apparatus adopts a configuration of opening and closing the opening of the nozzle guide for guiding the fuel filling nozzle inserted from the opening of the filler neck with a rotatable flapper. The flapper is attached so as to be biased upwardly by being pushed by the torsion coil spring and to be rotatable downwardly by being pushed by the fuel filling nozzle. The flapper opens the opening of the nozzle guide when it is pushed by the fuel filling nozzle inserted from the opening of the filler neck and rotated downwardly. When the fuel filling nozzle is removed, the flapper rotates upwardly by the torsion coil spring thereby closing the opening of the nozzle guide. Such a fuel filler port closing apparatus has a problem in that it is difficult to realize the processing accuracy of the flapper and the opening of the nozzle guide, and the assembly accuracy of the flapper and the nozzle guide as designed. Furthermore, since the amount of deflection of the seal packing attached to the flapper varies, the necessary sealability of the filler neck may become difficult to ensure.
JP 2007-331518 discloses a fuel filler port closing apparatus in which the bias of the flapper is made sufficiently strong while reducing the spring constant of each torsion coil spring and accommodating the bending stress in time of closure within the allowable level by forming the torsion coil spring as a double configuration. The fuel filler port closing apparatus of JP 2007-331518 ensures the sealability of the filler neck by strongly pressing the seal packing attached to the flapper against the peripheral edge (valve seat) of the opening of the nozzle guide.
U.S. Pat. No. 5,732,840 and U.S. Pat. No. 6,446,826 disclose a configuration in which a bearing hole of the rotation shaft of the flapper is formed as a long hole and the flapper is pressed and moved parallel with respect to the opening of the nozzle guide. The seal packing attached to the flapper then can be reliably pressed against the peripheral edge (valve seat) of the opening of the guide to ensure the sealability of the filler neck.
The fuel filler port closing apparatus disclosed in U.S. Pat. No. 5,732,840 and U.S. Pat. No. 6,446,826 excels in that the seal packing attached to the flapper is reliably pressed against the peripheral edge (valve seat) of the opening of the nozzle guide to ensure the sealability of the filler neck by simply forming the bearing hole of the rotation shaft of the flapper as a long hole.
In other words, the fuel filler port closing apparatus disclosed in U.S. Pat. No. 5,732,840 and U.S. Pat. No. 6,446,826 change the orientation of the flapper within the range of the vertically long hole in the peripheral direction to evenly press the seal packing against the peripheral edge (valve seat) of the opening of the nozzle guide while absorbing the variation in the amount of deflection. If the seal packing can be evenly pressed against the peripheral edge (valve seat) of the guide opening in the peripheral direction, the lowering in the processing accuracy of the flapper and the opening of the nozzle guide and the assembly accuracy of the flapper and the nozzle guide can be absorbed.
However, if the bearing hole is a long hole, the flapper may not smoothly rotate. For instance, as seen from FIG. 8, in a tilted orientation in which one end of the rotation shaft 601 is positioned at the upper end edge of one bearing hole 602 and the other end of the rotation shaft 601 is at the lower end edge of the other bearing hole 602, the rotation of the flapper 603 is inhibited by the mutual friction of bearing flanges since the bearing flange 604 of the flapper that passes the rotation shaft 601 therethrough tilts with respect to the bearing flange 605 of the nozzle guide. Flapper is thought to be easily tilted by pushed on its peripheral end with the fuel filling nozzle. In the worst case, the flapper 603 might be get caught between the flanges 605 in the state illustrated in FIG. 8. Furthermore, since the torsion coil spring 606 is normally attached to the rotation shaft 601, the bearing flange 604 of the tilted flapper may inhibit the movement of the torsion coil spring 606.